MIT OpenCourseWarehttp://ocw.mit.edu 6.453 Quantum Optical Communication Spring 2009 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms.September 4, 2008Optical and Quantum Communications Groupwww.rle.mit.edu/qoptics6.453 Quantum Optical CommunicationLecture 1Jeffrey H. Shapiro2www.rle.mit.edu/qoptics6.453 Quantum Optical Communication — Lecture 1! Handouts! Syllabus, schedule/policy, probability chapter, lecture notes, slides,problem set 1! Sign-up on class list! Introductory Remarks! Subject organization! Subject outline! Technical Overview! Optical eavesdropping tap — quadrature-noise squeezing! Action at a distance — polarization entanglement! Long-distance quantum state transmission — qubit teleportation3www.rle.mit.edu/qopticsOptical Homodyne Detection — Semiclassical! Signal is weak, LO is strong! Energy conservation! Detectors are noisy square laws! Output mean and varianceBalanced Homodyne Receiver4www.rle.mit.edu/qopticsOptical Waveguide Tap —!Semiclassical! Coupler is a beam splitter! Tap input is zero! Homodyne SNR at signal input! Homodyne SNR at signal output! Homodyne SNR at tap outputFused Fiber Coupler5www.rle.mit.edu/qopticsQuantum Homodyne Detection and Waveguide TapBalanced Homodyne ReceiverFused Fiber CouplerHomodyne SNR at signal outputHomodyne SNR at tap output6www.rle.mit.edu/qopticsBilliard-Ball Photons and the Poincaré Sphere! Polarization of -going photon:! Poincaré sphere representation! polarization measurement7www.rle.mit.edu/qopticsClassical Correlation vs. Quantum Entanglement! Classical-Correlated, Randomly-Polarized Photons! Source produces photon pair with completely random! Conditional probability given photon 1 is instead of! Maximally-Entangled Photons! Source produces photon pair with completely random! Conditional probability given photon 1 is instead of8www.rle.mit.edu/qopticsProperties of Single-Photon Polarization States! Polarization cannot be perfectly measured Æ! ¨ Polarization cannot be perfectly cloned! Photons can be lost in propagation:9www.rle.mit.edu/qopticsPhoton Polarization States Can Be TeleportedAliceBob10www.rle.mit.edu/qopticsThe Road Ahead: Problem Set 1, Lectures 2 and 3! Problem Set 1! Reviews of essential probability theory and linear algebra! Lectures 2 and 3:Fundamentals of Dirac-Notation Quantum Mechanics! Quantum systems! States as ket vectors! State evolution via Schrödinger’s equation! Quantum measurements — observables! Schrödinger picture versus Heisenberg
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